1. Field of the Invention
Embodiments of the present disclosure relate generally to methods and systems for simultaneous or near-simultaneous acquisition for borehole seismic in oilfield or related applications. However, identification of an exemplary field is for the purpose of simplifying the detailed description and should not be construed as a limitation. Various embodiments of the concepts presented herein may be applied to a wide range of applications and fields as appropriate.
2. Description of the Related Art
The following descriptions and examples are not admitted to be prior art by virtue of their inclusion in this section.
Hydrocarbon fluids such as oil and natural gas are obtained from a subterranean geologic formation, referred to as a reservoir, by drilling a well that penetrates the hydrocarbon-bearing formation. Knowing where the reservoir is located or the type of geological formation containing the reservoir is valuable in determining where to drill and in deciding what well servicing treatments may be needed to efficiently produce a reservoir. One method of mapping the area around a borehole uses acoustic source signals and acoustic receivers.
As the acoustic signals travel through the geological formations, their profiles are altered and then received by the acoustic receivers. By processing the waveforms and acoustic signals detected by the receivers, a representative indication of the location, composition, and extent of various geological formations may be obtained. The acoustic signals may include both sonic and seismic signals. An example of such systems is Schlumberger's VSI (Versatile Seismic Imager).
An acoustic system comprising acoustic sources and receivers may be configured to produce a 3D VSP (three-dimensional vertical seismic profile). To produce a 3D VSP surrounding a borehole, a large number of datasets must be produced and analyzed. For example, in a marine system, a boat or other vessel towing an acoustic source array may move in proximity to a rig in an ever expanding pattern, initiating source signals as the boat travels. The acoustic receivers may be located in a borehole located below the rig. However, this technique may take days to complete. Since rig time is typically measured in hours, the costs to perform a full 3D VSP can be quite substantial.